The problem with 'True' as an adjective or adverb is that the moment you see it you know that someone is going to rain on your parade. I mean, here you are relaxing with your single malt (OR beer or tequila or whatever, just so I don't get into an idiotic argument about the relative merits of various liquors...OR about the virtues of being teetotal) and your music of choice, murmuring to yourself, "This is bliss' and someone pops up with "Oh, yeah! Do you know what true bliss is?"; THAT puts paid to the evening, let me tell you.
Invariably, that someone IS a philosopher, yes. It is as though that THIS is a badge that identifies a philosopher - this finding of 'true' this and 'true' that. So, how do you expect Tiru to NOT acquire this badge?
Gunanalam saandror nalane piranalam ennalatthu ulaadhoon andru - Tirukkural
The only delight of the wise and good is that of good character; all else is dross - Loose Translation
Let us get the translation issues out of the way. 'Saandror' generally indicates 'wise people'. NOW, in those times, apparently 'wise' also connoted 'good' automatically; 'intelligent' was a whole different cup of tea but 'wisdom' also meant that the person concerned was as good as a saint. I mean, these were the times when 'knowledge' itself meant more spiritual knowledge than worldly knowledge, the latter being relegated to the 'skills' department. In these days when worldly-wise is the only wise there is (AND, no, I start from the day I was born when I say, 'these days' NOT from the day I retired!), I make it a point to add '...and good' to 'wise'.
Further, this 'nalan' or 'nalam' meant 'well-being' which can be translated to physical or mental well-being or both; it also means 'good' when it is used as an...err...adjective or adverb. I call it 'delight' because, after all, it was those times when mental well-being and mental goodness were being considered the acme of delight.
So, yes, Tiru says that the only delight that the wise and good seek is the delight that comes from inside...of good character traits. All else that comes is not of great consequence to them. Which, essentially, has passed down through the ages till it was discarded recently. THAT NOTHING is worth gaining at the cost of losing your character. (As someone in the relatively recent past said, "When Wealth is lost, nothing is lost; when Health is lost, something is lost; when Character is lost everything is lost". Who said it? I take no names for, after all, if I do we will only end up in a long discussion about vilifying OR praising the person and totally forgetting the issue we were discussing.)
THAT was the 'wise and good' and what they do. How nice for us that we are neither!